Pollution from Mexican semis is probably related to the quality of the diesel. They run a heavier cut than is allowed in the US.
Notice the usual extreme hypocrisy from the enviro-wacko EPA crowd on, not just allowing this, but insidiously “making” it happen. And meanwhile, they hamstring and penalize hard-working, legal and honest Americans trying to make a go of their small business.
Damned lying anti-American lefties. Words cannot express what I feel towards them. And it gets worse as every day goes by.